May 2, 2014

Has The Winning Formula For ‘Rock-Paper-Scissors’ Been Cracked?

Played for fun as a child and to settle bets as an adult, rock-paper-scissors is a game played around the world by people of all ages.

While winning the game may seem to be completely up to luck or fate, a team of Chinese researchers claims to have hacked the game and developed a winning strategy. According to a report published by the team, game participants tend to follow fairly predictable patterns of behavior. The study team based their strategy and conclusion on 300 rounds of rock-paper-scissors played by random pairings of 360 students.

The game is typically played as a best-of-three competition and the researchers said that the first round is actually completely random and can’t be predicted. But, what a person plays – whether it’s a rock, paper or scissors – and if they win can be used to gauge the next round.

If a person wins, they are most likely going to follow with the same play in the next round. If a player loses, they were found most likely to switch their play to what be them, i.e. rock becomes paper, paper becomes scissors, and scissors become rock. The researchers called this the "win-stay, lose-shift" strategy.

Previous research has asserted that the game functioned in alignment with the Nash equilibrium, which states that players will select each option equally over time. However, the new study suggested that players have a “conditional response” to events that unfold over the course of the game.

Study author Zhijian Wang from Zhejiang University told Lucy Kinder of The Telegraph that previous research may have reached this conclusion because the sample size wasn’t large enough. He added that it is hard to determine if the responses are "built in" to the brain, but said players seem to follow a programmatic routine.

"Our theoretical calculations reveal that this new strategy may offer higher payoffs to individual players," he said.

While the Chinese team may have developed a strategy that will increase your odds for winning at rock-paper-scissors, a group of Japanese robotics engineers has devised a robot that doesn’t just win every game – it wins every round.

The robot’s secret? Super-human vision and reflexes. The robot, with its unnaturally fast processing power, is able to see what its opponent is throwing and beat an opponent’s play before the hapless adversary can even finish completing their move.

“Recognition of human hand can be performed at 1 ms (millisecond) with a high-speed vision, and the position and the shape of the human hand are recognized,” the Japanese team said in a statement.

“The wrist joint angle of the robot hand is controlled based on the position of the human hand,” the statement continued. “The vision recognizes one of rock, paper and scissors based on the shape of the human hand. After that, the robot hand plays one of rock, paper and scissors so as to beat the human being in 1ms.”

The researchers said the technology behind the robot could be used for more practical applications in the future, like helping robots to react to human movements in a collaborative setting.